1. Field of the Invention
The present invention relates to a semiconductor memory device.
2. Description of the Related Art
A dynamic random access memory (DRAM) including one capacitor and one transistor (referred to as a cell transistor) has been widely used as a typical semiconductor memory device. A planar transistor has been conventionally used to form a DRAM; however, in accordance with miniaturization of a circuit, a method using a recessed channel array transistor (RCAT) in which a gate is arranged three-dimensionally so as to prevent leakage current due to a short-channel effect is now employed (see Non-Patent Document 1).